The present invention generally relates to techniques for recording/reproducing video data and audio data which have been compress-coded with respect to a disk-shaped recording medium such as a magnetic disk. More specifically, the present invention is directed to techniques capable of increasing a transfer rate of recording/reproduced data and also capable of readily managing addresses.
Various hard disk apparatuses are commercially available as auxiliary storage units for computer usage. A hard disk used in a hard disk apparatus as a storage medium is realized by that plural sheets of magnetic disks made by coating magnetic materials on flat boards are stacked and rotated at a speed of several thousands rpm (rotation per minute). The quantity of magnetic disks are determined based on memory capacities. Coaxial-shaped recording tracks are set on a recording surface of a magnetic disk. Then, in each of these recording tracks, data are recorded in a unit called as a sector (normally, 1 sector being equal to 512 bytes). A sector is defined by segmenting a recording track by a fan shape. A sector address is set to a sector. A data recording/reproducing position may be designated by designating this sector address.
The zone bit recording system has been introduced in a hard disk. As illustrated in FIG. 1, the zone bit recording system is intended to achieve high density in such a manner that the surface of the magnetic disk is subdivided into a plurality of zones in a coaxial shape, the signal transfer speed is stepwise changed every zone while increasing the sector density in the outer peripheral zone and decreasing the sector density in the inner peripheral zone, and thus the recording density on the surface is averaged. Such a system is called as a ZCAV (Zoned Constant Angular Velocity) system in contrast to the conventional CAV (Constant Angular Velocity).
A hard disk owns the following features because such a ZCAV system is employed. That is, as shown in FIG. 2, the data read/write transfer rate of the outer peripheral zone is high, and the data record/write transfer rate is stepwise lowered along the inner peripheral zone. As a consequence, the data read/write transfer rate is minimum in the innermost zone.
Sector addresses of sectors which correspond to data transmit/receive units with respect to an external system are allocated to these zones from the outer peripheral zone to the inner peripheral zone. A starting address is present in the outermost peripheral zone, whereas an end sector address is present in the innermost peripheral zone.
In connection with great progress of large memory capacities and low cost of hard disks as well as great advances in data compression techniques, video (picture) data and audio data may be compressed in accordance with the international standard data compression system of MPEG (Moving Picture Image Coding Experts Group), and the compressed data may be recorded and/or reproduced in/from hard disks.
Conventionally, hard disks have been used as storage media for storing computer data. As a result, if an external host system can correctly recognize a sector address position on a hard disk and can correctly read/write data at this sector address position, then it is not an important aspect as to how the data is arranged at which sector address position on this hard disk. That is, it is not important to grasp the actual data read/write transfer rate, and where the relevant data is arranged with respect to the sector address position.
However, in such a case that data such as video data is required to be continuously read and/or written in real time and further data having a large information amount is recorded and/or reproduced, if these data are arranged irrelevant to own sector address positions on the hard disk in a similar manner to the computer use, then the seek operation for transporting the magnetic head to a target track, and also the rotation waiting operation until the target sector is located upright the magnetic head will frequently occur while the data is recorded and/or reproduced. Accordingly, such a phenomenon will occur that the average data transfer rate is lowered, and thus the data cannot be recorded and/or reproduced in time on the side of the external host system.
Also, the maximum transfer rate at which the data can be recorded and/or reproduced from the external system side cannot be increased higher than the transfer rate of the innermost peripheral zone of the hard disk. Therefore, there is another problem that the transfer rate of the video data cannot be excessively increased.
For instance, as indicated in a transition diagram of data transfer operation as viewed from the host system side, as shown in FIG. 3, since a limit value of a data transfer rate on the host system side is lower than a limit value of a data transfer rate of a hard disk from a zone 1 up to a zone 3, the data is transferred at the transfer speed on the host system side. However, since the limit value of the data transfer rate on the host system side becomes higher the limit value of the data transfer rate on the hard disk side from a zone 4 to a zone 6, the data is transferred at the transfer rate on the hard disk side.
As a consequence, the transfer rate of the data recordable and/or reproduceable from the host system could not be increased higher than the transfer rate of the zone 6. Accordingly, since the transfer rate of the video data could not be increased so high, there is a further problem that the video data having the high image quality could not be recorded and/or reproduced.
The present invention has been made to solve the above-described problems, and therefore, has an object to provide a recording method/recording apparatus, a reproducing method/reproducing apparatus, a recording/reproducing method, a recording/reproducing apparatus, and a disk-shaped recording medium, by which video (picture) data with a high image quality can be recorded and/or reproduced.
To achieve the above-described object, the method according to the present invention is featured by that when at least image data is recorded and/or reproduced with respect to a disk-shaped recording medium, the method records and/or reproduces image data having a large data amount per unit time in an outer peripheral sided region of the disk-shaped recording medium; and records and/or reproduces one of image data and system data, having a small data amount per unit time in an inner peripheral sided region of the disk-shaped recording medium.
Also, the apparatus according to the present invention is featured by comprising: first means for recording and/or reproducing image data with respect to a disk-shaped recording medium in which an outer peripheral sided region thereof is recordable and/or reproduceable at a higher rate than that of an inner peripheral sided region thereof; and second means for designating an attribute of image data recorded and/or reproduced in/from the disk-shaped recording medium; wherein: when the second means designates image data having a large data amount per unit time, the first means records and/or reproduces the image data having the large data amount per unit time in the inner peripheral sided region of the disk-shaped recording medium, whereas when the second means designates image data having a small data amount per unit time, the first means records and/or reproduces the image data having the small data amount per unit time in/from the inner peripheral sided region of the disk-shaped recording medium.
Furthermore, a disk-shaped recording medium, according to another aspect of the present invention, is featured by that image data having a large data amount per unit time can be recorded and/or reproduced in an outer peripheral sided region of the disk-shaped recording medium; one of image data and system data, having a small data amount per unit time can be recorded and/or reproduced in an inner peripheral region thereof; and information used to discriminate a relationship between each of the regions and a transfer rate of data is saved.
In this case, the image data having a large data amount per unit time corresponds to, for instance, such moving picture image data which requires the real time characteristics. Also, the image data having a small data amount per unit time corresponds to, for example, such still picture image data which does not require the real time characteristics. Then, the system data implies, for instance, time information and file information used on the system side.
As a result, according to the present invention, the recording region is determined by considering the attribute of the data to be recorded. The moving picture image data which requires the higher data transfer rate is arranged in the outer peripheral-sided region of the disk where the data can be transferred in high speed. Accordingly, the information amount of the single moving picture image data can be increased, and thus the image quality thereof can be improved.
Since only the moving picture image data is recorded in such an area for recording the moving picture image data, there is a small possibility such that the data are arranged at random on the disk-shaped recording medium as in the conventional system. As a consequence, the total time required for the seeking operation and the rotation waiting operation could be reduced, and in view of this point, the data transfer rate could be increased.